Muscular System Lesson

The word muscle is derived from the Latin term musculus, meaning "little mouse". This Latin term could be due to the shape of some muscles or because muscles contracting under the skin can look like a mouse moving under a rug.

• 40% of your body weight is muscle

• Approximately 650 muscles

• Muscles only pull (They can't push)

• You have over 30 facial muscles

• Eye muscles move more than 100,000 times a day

• It takes 17 muscles in the face for us to smile and 43 muscles to frown.

• Maintain body temperature

• Move bones

• Maintain posture and body positioning

• Store nutrient reserves

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• Contractions of smooth muscle are involuntery.

• Involuntary means it happens without your control.

• Found in the walls of internal organs

• Examples:

• walls of blood vessels

• eye

• GI tract

• stomach

It is called smooth muscle because the fibers lay flat like a sheet of paper.

• Only found in the walls of the heart.

• The muscle is arranged in bundles.

• The muscle is called striated because it looks like stripes.

• Muscle is involuntary.

• Works with the skeletal system for movement

• Made up of long cylindrical fibers running the length of the muscle

• Voluntary Muscles

• Usually work in pairs

Skeletal muscle can be further divided into two types, slow twitch and fast twitch.

Slow twitch (Type I) muscle contain proteins that give it a rich red color.

This muscle carries more oxygen efficiently and using fats, proteins or carbs as energy slow twitch muscle fibers contract over a long period of time.

Therefore type I muscle fiber works well for aerobic sports such as long distance running and cycling.

Fast twitch (Type II) muscle is whiter in color as it has less myoglobin (a oxygen carrying protein). Fast twitch fibers contract quickly and powerfully, however they fatigue rapidly. Therefore type II muscle fiber is useful for anaerobic exercise such as sprinting or for strength sports like weightlifting.

Muscles that bend parts of your body are called flexors.

Muscles that straighten parts of your body are called extensors